Search for remains of Jimmy Hoffa

Law enforcement officials from the Michigan State Police help search the area in Oakland Township, Mich., Tuesday, June 18, 2013 where officials continue the search for the remains of Teamsters union president Jimmy Hoffa who disappeared from a Detroit-area restaurant in 1975. (AP Photo/Carlos Osorio)

Members of the FBI evidence response team look over an area being cleared in Oakland Township, Mich., Tuesday, June 18, 2013 where officials continue the search for the remains of Teamsters union president Jimmy Hoffa, who disappeared from a Detroit-area restaurant in 1975. (AP Photo/Carlos Osorio)

A law enforcement official from the FBI measures an area in Oakland Township, Mich., Tuesday, June 18, 2013 where officials continue the search for the remains of Teamsters union president Jimmy Hoffa who disappeared from a Detroit-area restaurant in 1975. The search follows claims made in February by reputed Mafia captain Tony Zerilli, who told Detroit TV station WDIV that he knew where Hoffa was buried. (AP Photo/Carlos Osorio)

Members of an FBI evidence response team look over an area being cleared in Oakland Township, Mich., Tuesday, June 18, 2013 where officials continue the search for the remains of Teamsters union president Jimmy Hoffa, who disappeared from a Detroit-area restaurant in 1975. (AP Photo/Carlos Osorio)

FILE - Jimmy Hoffa is shown in this 1975 file photo. Hoffa, father of current Teamsters President James P. Hoffa, disappeared from the parking lot of the Machus Red Fox restaurant in Oakland County's Bloomfield Township in July 1975. Federal agents revived the hunt for the remains of Jimmy Hoffa on Monday June 17, 2013, digging around in a suburban Detroit field where a reputed Mafia captain says the Teamsters boss' body was buried. (AP Photo/Richard Sheinwald)

FILE - In this Monday, June 17, 2013 file photo, members of the FBI Evidence Response Team survey an area in Oakland Township, Mich., where officials search for the remains of Teamsters Union president Jimmy Hoffa who disappeared from a Detroit-area restaurant in 1975. The search follows claims made in February by reputed Mafia captain Tony Zerilli, who told Detroit TV station WDIV that he knew where Hoffa was buried. (AP Photo/Carlos Osorio, File)

FILE - This July 26, 1959 file photo shows Teamsters Union president Jimmy Hoffa in Washington. Federal agents revived the hunt for the remains of Hoffa on Monday, June 17, 2013, digging around in a suburban Detroit field where a reputed Mafia captain says the Teamsters boss' body was buried. Authorities used excavation equipment to root around in the Oakland Township property, about 25 miles north of Detroit. (AP Photo/File)

FILE - In this June 3, 1974 file photograph, teamsters president Jimmy Hoffa is shown in Washington. The Teamsters leader was last seen in July 1975 at a restaurant in Oakland County's Bloomfield Township in Michigan. Federal agents revived the hunt for the remains of Jimmy Hoffa on Monday June 17, 2013, digging around in a suburban Detroit field where a reputed Mafia captain says the Teamsters boss' body was buried. (AP Photo, File)

FILE - In this Aug. 21, 1969 file photo, Teamsters Union leader James Hoffa is shown in Chattanooga, Tenn. The FBI has seen enough merit in a reputed Mafia captain's tip to once again break out the digging equipment to search for the remains of Hoffa, last seen alive before a lunch meeting with two mobsters nearly 40 years ago. Tony Zerilli told his lawyer that Hoffa was buried beneath a concrete slab in a barn in a field in suburban Detroit in 1975. (AP Photo/File)

FILE - In this Sept. 28,1975 file photo, Michigan State police and local authorities watch as a backhoe digs, searching for the body of missing ex-Teamster president James R. Hoffa, in Waterford Township, Mich. The search turned up nothing. The FBI has seen enough merit in a reputed Mafia captain's tip to once again break out the digging equipment to search for the remains of Hoffa, last seen alive before a lunch meeting with two mobsters nearly 40 years ago. Tony Zerilli told his lawyer that Hoffa was buried beneath a concrete slab in a barn in a field in suburban Detroit in 1975. (AP Photo/File)

FILE - This March 22, 2009 file photo shows Giants Stadium from the air, in East Rutherford, N.J. Former Teamsters boss Jimmy Hoffa was last seen in July 1975 at a restaurant in Oakland County's Bloomfield Township in Michigan. Self-described hit man Donald "Tony the Greek" Frankos claims ex-Teamsters boss Jimmy Hoffa was buried under the western end zone at the Giants Stadium, but the FBI found no evidence to support the claim. (AP Photo/Mark Lennihan, File)

FILE - In this Friday, Sept. 28, 2012 file photo, police tape blocks a driveway where authorities drilled for soil samples in the floor of a shed at a Roseville, Mich., home, after police were told by a source that former Teamsters boss Jimmy Hoffa was buried beneath the driveway. But the search turned up nothing. Now, the FBI has seen enough merit in a reputed Mafia captain's tip to once again break out the digging equipment to search for the remains of Hoffa, last seen alive before a lunch meeting with two mobsters nearly 40 years ago. Tony Zerilli told his lawyer that Hoffa was buried beneath a concrete slab in a barn in a field in suburban Detroit in 1975. (AP Photo/Paul Sancya, File)

FILE - In this Friday, May 28, 2004 file photo, television crews set up camp outside a house in northwest Detroit, where investigators looking into the 1975 disappearance of Teamsters boss Jimmy Hoffa ripped up floor boards. The FBI has seen enough merit in a reputed Mafia captain's tip to once again break out the digging equipment to search for the remains of Hoffa, last seen alive before a lunch meeting with two mobsters nearly 40 years ago. Tony Zerilli told his lawyer that Hoffa was buried beneath a concrete slab in a barn in a field in suburban Detroit in 1975. (AP Photo/Carlos Osorio, File)

FILE - In this July 16, 2003 file photo, authorities search under a backyard pool in Hampton Township, Mich., for evidence linked to the disappearance of ex-teamster boss Jimmy Hoffa. The search turned up nothing. The FBI has seen enough merit in a reputed Mafia captain's tip to once again break out the digging equipment to search for the remains of Hoffa, last seen alive before a lunch meeting with two mobsters nearly 40 years ago. Tony Zerilli told his lawyer that Hoffa was buried beneath a concrete slab in a barn in a field in suburban Detroit in 1975. (AP Photo/Paul Sancya, File)

FILE - In this Sept. 30, 1957 file photo, Jimmy Hoffa, Teamsters vice president and leading candidate to succeed Dave Beck as the IBT's new president, waves to delegates at the opening of the Teamsters Union convention at Miami Beach, Fla. Hoffa's mysterious disappearance, assumed death and myriad searches for his body have been the stuff of urban legends for more than three decades and continue with the most recent report that the former Teamsters chief's remains are buried beneath a concrete slab in a barn in a field in suburban Detroit. (AP Photo/File)

FILE - In this Dec. 5, 1975 file photo, a man walks over a rubble field in Jersey City, N.J., one of the locations where authorities searched for the body of missing former Teamster boss Jimmy Hoffa. The search turned up nothing. The FBI has seen enough merit in a reputed Mafia captain's tip to once again break out the digging equipment to search for the remains of Hoffa, last seen alive before a lunch meeting with two mobsters nearly 40 years ago. Tony Zerilli told his lawyer that Hoffa was buried beneath a concrete slab in a barn in a field in suburban Detroit in 1975. (AP Photo/File)

FILE - In this Friday, May 19, 2006 file photo, searchers in formation inspect a field at Hidden Dreams Farm in Milford Township, Mich., in the search for the body of former Teamsters leader Jimmy Hoffa. The FBI called in archaeologists and anthropologists to search the farm for Hoffa who disappeared in 1975. The search turned up nothing. (AP Photo/John M. Galloway, File)